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Re: [Xen-devel] [PATCH] ioemu: need probe backing file format

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Subject: Re: [Xen-devel] [PATCH] ioemu: need probe backing file format
From: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
Date: Tue, 18 Aug 2009 17:23:28 +0100
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Wei Kong writes ("[Xen-devel] [PATCH] ioemu: need probe backing file format"):
> Revert changeset 17646
> Due to qcow2 also has backing file.

I'm not sure what you mean exactly or what you are trying to achieve,
but guessing slightly:

Do you mean that you have a qcow2 image which has a backing file other
than in raw format (eg, another cow image) ?  If so that is sadly not
supported in Xen; the version of qemu we currently have has no way of
recording the backing file format and format probing is a security
vulnerability, as has been discussed several times.

> -        ret = bdrv_open2(bs->backing_hd, backing_filename, open_flags,
> &bdrv_raw);
> +        ret = bdrv_open(bs->backing_hd, backing_filename, open_flags,
> &bdrv_raw);

In any case this is wrong because bdrv_open has one fewer arguments
than bdrv_open2 ...


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